Although it has previously not been known that one compound alone can imitate true to nature the complex olfactory impression of lily of the valley, hydroxycitronellal (3,7-dimethyl-7-hydroxyoctan-1-al) comes remarkably close to the odor of lily of the valley. In combination with other lily of the valley odorants such as LYRAL.RTM. (4-(4-hydroxy-4-methylpent-1-yl)-cyclohex-3-ene-1-carboxaldelhyde), LILIAL.RTM. (3-(4-tert-butylphenyl)-2-methylpropanal) and/or DUPICAL.RTM. (4-(octahydro-4,7-methano-5H-inden-5-ylidene)butanal) (G. Frater, J. A. Bajgrowicz, P. Kraft, Fragrance Chemistry, Tetrahedron 1998, 54, 7633-7703) it is, however, possible to come very close to the natural standard. The aldehyde group is common to all of these mentioned odorants with lily of the valley character. This gives rise to an instability of the compounds in oxidizing or strongly alkaline media.
Some lily of the valley odorants without an aldehyde function have been found in the alcohols MAYOL.RTM. (4-(1-methylethyl)cyclohexylmethanol), MAJANTOL.RTM. (2,2-dimethyl-3-(3-methylphenyl)propanol), FLOROL.RTM. (tetrahydro-4-methyl-2-(2-methylpropyl-2H-pyran-4-ol) and MUGETANOL.RTM. (U. Harder, E. Oelkers, in: Recent Developments in Flavor and Fragrance Chemistry, published by VCH, Weinheim, 1993, pp. 162-163). Moreover, the carbon analogue to FLOROL.RTM. with very similar olfactory properties to FLOROL.RTM. has become known from WO 98/47842. However, these alcohols possess neither the naturalness, radiating strength and crispness nor the olfactory strength of the aforementioned aldehydes, and the need for a replacement substance for the lily of the valley aldehydes therefore continues to exist. There is therefore a requirement for additional lily of the valley odorants, especially with a functional group other than the aldehyde function, in order to obviate the previously mentioned disadvantages.
In GB Patent No. 1,167,776 claim is made, inter alia, to supposed compounds of general formulae Ia and Ib. ##STR1##
From the examples given therein it is, however, evident that compounds falling within formulae Ia and Ib were never prepared in pure form. It has now been established that this is also not at all possible on the basis of the route of preparation described. In fact, in the dehydration of the 1,6-diols which are the basis for the compounds Ia and Ib there is obtained a mixture of all three possible isomeric octan-1-ols with respect to the double bond. For example, in the case of compounds Ib there are obtained according to the given process the alcohols (6E)-6-ethyl-3-methyloct-6-en-1-ol (ca. 30%), (6Z)-6-ethyl-3-methyloct-6-en-1-ol (ca. 30%) and 6-ethyl-3-methyloct-5-en-1-ol (ca. 40%). As mentioned in the patent, this mixture of compounds Ib has, in fact, the indicated odor of lily of the valley and rose, but the odor of the rose side notes is unpleasantly musty. Because of this musty rose-like side note, the mixture Ib cannot completely satisfy the requirements of a lily of the valley odorant without an aldehyde function. It has therefore been used in perfumery only sporadically. Today, there is practically no commercial demand for this mixture. The production of the mixture Ib has in the meanwhile been discontinued for this reason.